Presently-known multi-waveguide optical conductors are generally in the form of tapes containing 4, 6, 10, 12, or 18 conventional individual optical fibers embedded in a resin. Each conventional individual fiber comprises a core and optical cladding based on silica and having an outside diameter of the order of 40 .mu.m. The optical cladding is itself surrounded by a layer of silica having an outside diameter of 125 .mu.m which is covered with a plurality of organic protective layers to a total outside diameter equal to about 250 .mu.m.
By way of example, the minimum known transverse dimensions for a six-fiber tape are about 1.65 mm by 0.3 mm. Given the large number of tapes used in building up an optical cable, it is essential to improve the compactness of such tapes.
A multicore optical fiber is also known, as described in the article by Ryszard S. Romaniuk and Jan Dorosz entitled "Coupled/non-coupled wave transmission in long length of multicore optical fibers" published in the 10th Meeting of European ECOC 84, Stuttgart, pp. 202-203. During fiber-drawing, the core glass of the preform passes through a multihole diaphragm; that method is difficult and expensive and it gives rise to a fiber having a plurality of cores that are deformed.